|St Ignatius' College, Riverview, Sydney, AU|
The only detail of the allegation contained in the letter is that it concerned "child sexual abuse over 30 years ago".
Dr Hine said it was with "some sadness" that he wrote to the school community about the allegation which had been passed on to him from the professional standards office of the Australian Province of the Society of Jesus.
"There are clear limits on what I am able to reveal about the allegations," Dr Hine wrote. "Despite this, I believe it important to inform you about the situation as I understand it and to offer reassurance that such matters are the object of direct and sustained vigilance at the school."
Dr Hine said he would also be informing current students about the allegations.
He said Riverview took seriously its duty of care to the entire school community and that their procedures to safeguard students were of the highest standard.
Anyone with concerns related to child abuse or other "professional standards matters" should contact the Australian Province of the Society of Jesus or Dr Hine personally, he wrote.
"For a long time Riverview has had a proud history of education and care for boys," Dr Hine wrote. "This situation presents a salient reminder of the need to protect our young people both in policy and in practice."
The north shore private school boasts notable alumni including Prime Minister Tony Abbott and the Archbishop of Sydney Anthony Fisher. Former NSW premier Nick Greiner and federal minister Barnaby Joyce also attended.
In 1997 a teacher at the school, Peter Bohrsmann took his own life on school grounds after a detailed complaint was made to police about him.
The 57-year-old classics teacher, himself a former pupil, was found dead in his car with the engine running close to the Jesuit school's boat shed. His body was discovered two days after he had protested his innocence when confronted about the anonymous allegation.
It is not know if the current allegation before police relates to that matter or a separate incident.
Comment was being sought from the NSW police.